Polyvinyl acetal resin sheets containing di-isoamyl maleate



Patented Oct. 15, 1940 PATENT OFFICE POLYVINYL ACETAL RES SHEETS CON- TAININ G DI-ISOAMYL MALEATE Jack J. Gordon, Kingsport, Tenn., assignor to Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey No Drawing. Application October 20, 1939,

' Serial No. 300,432

3 Claims.

This invention relates to polyvinyl acetal resin sheets, and more particularly to sheets suitable for the manufacture of safety glass.

One object of my invention is to produce com- 5 positions of matter which can be made into permanently transparent sheets suitable for use in laminated, shatter-proof glass. Another object is to produce compositions which can be rolled, extruded, molded, or otherwise worked into relatively thick sheets and massive plastics. Other objects will hereinafter appear.

I have discovered that di-isoamyl maleate is a useful plasticizer for certain polyvinyl acetal resins, namely the polyvinyl acetal resins in which a predominating proportion of the acetal groups are selected from the group consisting of polyvinyl acetaldehyde acetal groups and polyvinyl butyraldehyde acetal groups. Moreover, I have discovered that when 40 or more parts of diisoamyl maleate is used with 100 parts of polyvinyl acetaldehyde or butyraldehyde acetal resin, an unusual and remarkable efiect is obtained which I may call elasticizing. That is to say, a sheet of polyvinyl acetaldehyde acetal resin containing about 40 or more parts of di-isoamyl maleate per 100 parts of resin possesses the property which, in the rubber industry, is known as "nerve: namely, the property of stretching to a considerable extent when tension is exerted upon it, and returning to its original dimensions when the tension is released. This property 'renders such sheets, which I shall call rubbery sheets, particularly useful in the manufacture of shatter-proof glass.

Sheets for use in laminated glass may be made by dissolving the polyvinyl acetaldehyde of butyraldehyde acetal resin and the di-isoamyl maleate in a suitable volatile solvent or solvent mixture, such, for instance, as acetone, methanol. acetonemethanol mixtures, ethylene chloride-methanol mixtures, etc., about 300 to 500 or more parts of the solvent or solvent mixture being used per- 100 parts or the resin. The solution is then cast as a sheet, the volatile solvent evaporated, and the sheet stripped from the casting surface.

Sheets for use in laminated glass may also be made without the use of volatile solvent by extrusion, for example, in-the manner set forth in application Serial No. 147,934 of John S. Kimble and Ernest C. Blackard, filed June 12, 1937. For example, 40 or more parts of di-isoamyl maleate and 100 parts of a polyvinyl acetaldehyde or butyraldehyde acetal resin may be mixed in a suitable, jacketed mixer at a low temperature, for example 10 C., and the mixture may then be worked on hot rolls, in the manner described in U. S. Patent 2,048,686 of F. R. Conklin, until complete homogenization has taken place. The mass thus produced may then be extruded through an annular die, and the tube so formed slit-to form 5 a sheet. 1

The polyvinyl acetal resins can be prepared by reacting polyvinyl alcohol with an aldehyde in the presence of an acetal condensation catalyst, e. g., a mineral acid. These resins can also be 10 prepared by simultaneously de-esterifying a polyvinyl aliphatic esterand reacting the de-esterification product with an aldehyde in the presence of a de-esterifying catalyst and acetal condensation catalyst. Mineral acids are catalysts'for 15 both de-esterification and acetal formation. 7

Examples of the preparation of polyvinyl acetaldehyde acetal resins may be found in U. S. Patent 2,044,730, Example 1;- U. S. Patent 1,955,068, Example 2'; U. S. Patent 2,036,092, Ex 20 amples 4, 5 and 6; British Patent 466,598, Examples 1, 2, 3, 4 and 7; British Patent 404,279, Examples 1, 2,4,- 5, 6, 7 and 8; U. S. Patent 1,990,399; and French Patent 808,578, Examples 1, 2 and 3.

Examples of the preparation of polyvinyl butyraldehyde acetal resins may be found in U. S. Patent 2,044,730, Examples 2, 5 and 6; British Patent 466,598',-Example 5; French Patent 813,303, Example 1; French Patent 313,514, 30

Examples 1, 2, 3 and 4; and British Patent 459,878, Examples 1, 2, 5, 6, 7, 8, 9 and 10.

'An example of the preparation of a polyvinylbutyraldehyde acetaldehyde mixed acetal resin is given in French Patent 813,303, Example 2.

What I claim as my invention and desire to .be secured by Letters Patent otthe United States is:

l. A transparent, rubbery sheet comprising parts of a polyvinyl acetal resin, a predominating proportion of whose acetal groups are selected from the group consisting of acetaldehyde acetal groups and butyraldehyde acetal groups, and at least 40 parts, approximately, of di-isoamyl 45 maleate.

2. A transparent, rubbery sheet comprising 100 parts of a polyvinyl acetaldehyde acetal resin and at least 40 parts, approximately, of di-lsoamyl maleate. 5o

3. A transparent, rubbery sheet comprising 100 parts of a polyvinyl butyraldehyde acetal resin and at least 40 parts, approximately, of dl-isoamyl maleate.

JACK J.- GORDON. 

